CAMP—See Cyclic adenosine

If MLCK activates contraction by increasing myosin phosphorylation, then an increase in the activity of myosin light chain phosphatase, MLCP, by decreasing the fraction of myosin which is phosphorylated, should lead to relaxation from the active (contractile) state. Cyclic adenosine monophosphate (AMP) is a strong inhibitor of smooth muscle contraction and it has been suggested that activation of MLCP could result from its phosphorylation via cAMP activated protein kinase (see Figure 5). 

Corey lactol, 4 Cormethasone acetate, 194 Cormethasone acetate, 196 Cortisone, 176, 179 Cortivazol, 191 Cotinine, 235 Curare, 162 Cgclacillin, 439 Cgclazocine, 327 Cyclic adenosine monophosphate, see CAMP Cgclobendazole, 353 Cyclopropanation, 32, 166, 168, 174. 223, 297 Cgheptamide, 222 Cypenamine, 7 Cyprazepam, 402 Cyprolidol, 31 Cyproquinate, 368 Cyproterone acetate, 166 Cyproximide, 293... 

The activation of adenylyl cyclase enables it to catalyze the conversion of adenosine triphosphate (ATP) to 3 5 -cyclic adenosine monophosphate (cAMP), which in turn can activate a number of enzymes known as kinases. Each kinase phosphorylates a specific protein or proteins. Such phosphorylation reactions are known to be involved in the opening of some calcium channels as well as in the activation of other enzymes. In this system, the receptor is in the membrane with its binding site on the outer surface. The G protein is totally within the membrane while the adenylyl cyclase is within the membrane but projects into the interior of the cell. The cAMP is generated within the cell (see Rgure 10.4). 

Glucagon appears to exert its effects on liver cells by a classic adenyl cyclase-cyclic adenosine monophosphate (cAMP) second messenger system (see Chapter 4).93 Glucagon binds to a specific receptor located on the hepatic cell membrane. This stimulates the activity of the adenyl cyclase enzyme that transforms adeno-... 

In an alternative pathway, acetylcholine stimulates a smooth-muscle cell-membrane receptor to enhance the activity of adenyl cyclase. Adenyl cyclase increases the conversion of cyclic adenosine triphosphate to cAMP, a potent muscle relaxant. Similarly to cGMP, cAMP decreases intracellular calcium concentrations to produce smooth-muscle relaxation in cells of the arteries and cavernosal sinuses. Arterial blood flow to and blood filling of the corpora are enhanced, and a penile erection results (see Fig. 81-2). ... 

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